This invention resides in the structure of an intraocular lens which is implanted in an eye from which extraction has been made of a cataractous lens. The field of intraocular lens implants is a highly developed, sophisicated, medical technology. These prosthetic, or artificial, lenses are implanted following cataract surgery in either the anterior chamber or the posterior chamber of the eye. Because of the very small spaces involved, and the very delicate nature of the eye tissue, the surgery must be precise and the lens implant must be readily insertable as well as both safe and effective. Ever since the first intraocular lens was implanted, opthamologists have been searching for a universal lens, one that not only could be used for intracapsular and extracapsular implantation in either the anterior or posterior chamber of an eye but could also fit into any sized eye chamber. The lens of this invention fulfills all of these requirements.
The most commercially used intraocular lens is the Shearing Lens (U.S. Pat. No. 4,159,546) which is described for use in a posterior chamber of an eye. This lens is supported in the eye chamber by two opposed filamentous strands with one end connected to the body of the lens and the other end being free-floating and pointed resulting in a snag-prone support. The patent to Shearing is representative of the first generation technology of intraocular lens which neither required suturing nor clipping to part of the eye structure. This lens is also designed to be inserted in the posterior chamber of the eye and is generally supported by the rear wall, or posterior capsule, of the posterior chamber. The universal intraocular lens of the present invention, unlike the lens of Shearing, is designed to be functional and effective in either the anterior or the posterior chamber. The Shearing lens uses a haptic loop or flexible strand which includes a substantially straight leg portion extending away from the lens body and a curved or arch portion. The strands terminate in a free end. Shearing states that the free end is directed back toward the lens body to prevent the strand end from being pointed or jabbed against the delicate tissue within the eye during and after implantation. Thus, Shearing recognizes that damage to the eye tissue from the free end of the supporting strand of the lens can occur. The possibility of eye damage from the free end of the supporting strand with lenses, such as that of Shearing is enhanced by the surgical technique, known generally as "dialing," by which these lenses must be inserted. This requires that the lens to be rotated as it is inserted and significantly increases the risk that the free end of the flexible strand will catch on and damage eye tissue.
The applicant, who is an eye surgeon, is one of several thousands of surgeons who has been using this Shearing Lens implant. He has found that implanting this lens requires a great deal of training to implant the superior free pointed arched strand without injury to eye tissue. Proper centration often requires movement of the supporting strand which inevitably causes injury to eye tissue. A left-handed surgeon or a novitiate requires more movement for centration resulting in eye tissue injury. Knowing of these difficulties associated with implanting a Shearing Lens, applicant experimented to eliminate the free-flowing snag-prone point of the Shearing retaining filament supports. Blunting the point was not the solution. Applicant tried to use three or four retaining filaments but surprisingly found that the use of only two filaments with the point continued to form a substantially closed loop when molding it in one piece of polymethylmethacrylate would overcome the difficulties faced when using the Shearing Lens. Closing the loop resulted in a snag-free lens which upon implantation, inherently centers while the filamentous supports can then adjust to fit any sized eye chamber.
This application is filed to include the feature that the loop being formed does not have to be closed integrally with the strand. So long as the loop is formed it may end at the strand and not be integral therewith. This modification occurred during manufacture because it reduces the cost of manufacture but also provides the snag resistant feature. The present invention is directed to a one-piece intraocular lens which can be implanted in either the anterior or the posterior chambers of the eye. The lens body is supported by at least two flexible positioning and supporting elements which are integrally formed with the lens body and extended from the periphery of the lens body. The supporting elements of the invention define a continuous curved arc having a diameter of curvature greater than the diameter of the lens body. The arc is curved toward the lens surface. Snag-resistant means are integrally formed on the free end of the flexible supporting and positioning elements. In one form of the invention, the snag-resistant means is turned toward the supporting elements and terminates adjacent to, but spaced from, the elements. In another form of the invention the snag-resistant means comprises two bent arms, with one arm bent towards the lens circumference, while the second arm is bent away from the lens circumference. The two arms terminate adjacent to one another at a position opposite from the free end of the supporting elements. The present invention overcomes any danger of the free end of an intraocular lens causing damage to the eye tissue by the use of snag-resistant means on the free end of the flexible positioning and supporting strands of the lens. These snag-resistant supports at the end of the haptic loops or supporting strands reduce any possibility of hooking the iris when the lens is inserted in the posterior chamber. Additionally, due to the unique positioning of the haptic loops which define a continuous, curved arc having a diameter greater than the diameter of the lens body, the lens need not be dialed into place when inserted in the posterior chamber.